Quantum computers can work millions of times faster than regular computers, but they need a separate network for quantum communications for long-distance communication. Researchers at NASA’s Jet Propulsion Laboratory and Caltech have created a device that can accurately count a large number of single photons, which are quantum particles of light, so they can set up this kind of network. The Performance-Enhanced Array for Counting Optical Quanta (PEACOQ) detector is like measuring individual drops of water being sprayed by a firehose. It can tell within 100 trillionths of a second when each photon hits at a rate of 1.5 billion photons per second. No other detector can match this rate of finding things.

Ioana Craiciu, a postdoctoral scholar at JPL and a PEACOQ project team member, is the study’s lead author. He talks about these results: “Transmitting quantum information over long distances has, so far, been very limited,” Moreover, he said. “A new detector technology like the PEACOQ that can measure single photons with a fraction of a nanosecond precision enables sending quantum information at higher rates, farther.”

PEACOQ: High-Speed Quantum Communications
Credits: NASA/JPL-Caltech

A dedicated Network is Required:

In traditional computers, information is transformed into a series of ones, zeros, or bits, which are then copied and sent through modems, telecommunication networks, cables, and optical fibers. They travel through the airwaves as flashes of light or radio waves combined at the other end to make the original data.

On the other hand, quantum computers used in quantum Communications use qubits, bits stored in elementary particles like photons and electrons that can’t be copied or sent without damage. Also, quantum information sent through encoded photons on optical fibers loses its quality after only a few miles. This would make a future quantum network much smaller.

PEACOQ Detector
Credits: NASA/JPL-Caltech

To resolve these problems, quantum computers must talk to each other through a free-space optical quantum network. This network could have “nodes” in space, like satellites in orbit, that send data by making pairs of entangled photons and sending them to two quantum computer terminals on the ground that are hundreds or even thousands of miles apart.

The close connection between entangled photon pairs causes the measurement of one to instantaneously impact the results of measuring the other, regardless of the distance between them. However, for these entangled photons to be successfully received by a quantum computer’s terminal on the ground, a high-sensitivity detector, such as PEACOQ, is necessary to accurately measure the timing of each photon’s arrival and transmit the associated data. To successfully transmit entangled photons over long distances in quantum communications, a high-sensitivity detector like PEACOQ is required to measure the timing of each photon’s arrival and transmit the associated data accurately.

Superconducting Plumage:

The detector is so tiny that it only takes up 13 microns of space. It comprises 32 superconducting nanowires made of niobium nitride placed on a silicon chip and linked by wires that spread like a bird’s feathers. Each nanowire is 10,000 times thinner than a single human hair.

Superconducting Plumage
Credits: NASA/JPL-Caltech

The Space Operations Mission Directorate’s Space Communications and Navigation (SCaN) program paid for developing the PEACOQ detector. The Microdevices Laboratory at JPL made it. To keep the nanowires in a superconducting state, the detector must be kept at a cryogenic temperature of only one degree above absolute zero, or -458 degrees Fahrenheit (-272 degrees Celsius). This allows nanowires to convert photons into quantum data-carrying electrical pulses.

The PEACOQ detector has to be able to find a single photon, but it also has to handle multiple photons hitting it simultaneously. When a photon hits a nanowire in a detector, the wire can’t pick up another photon quickly. This is called “dead time.” But each nanowire is made to have as little dead time as possible, and the PEACOQ detector has 32 nanowires so that other wires can still pick up photons while one is in slow time.

“In the near term, PEACOQ will be used in lab experiments to demonstrate quantum communications at higher rates or over greater distances,” Further says. “In the long term, it could provide an answer to the question of how we transmit quantum data around the world.”

Deep Space Test
Credits: NASA/JPL-Caltech

Deep Space Test:

PEACOQ is part of NASA’s broader initiative to establish free-space optical communications between space and the Earth. This device is based on the detector created for NASA’s Deep Space Optical Communications (DSOC) technology demonstration. Scheduled to launch later in 2023 with the Psyche mission, DSOC will illustrate how high-bandwidth optical communications can function between Earth and deep space in the future. While DSOC does not involve transmitting quantum information, its ground terminal at Caltech’s Palomar Observatory requires the same level of sensitivity to detect individual photons arriving from the DSOC transceiver, which travels through deep space via lasers.

JPL’s Matt Shaw advises the superconducting detector team: “It’s all kind of the same technology with a new category of the detector,” Moreover, he said. “Whether that photon is encoded with quantum information or whether we want to detect single photons from a laser source in deep space, we’re still counting single photons.”


Published by: Sky Headlines